Biological and chemical remediation technologies offer the advantage of partial or complete degradation of Superfund chemical rather than simple transfer from one compartment to another. The ultimate goal of these technologies is the complete conversion of toxic chemicals to their mineral end products such as CO2 C1- and H20. Frequently however intermediates are produced from the partial transformation of Superfund chemicals. These intermediates may have sufficient stabilities so that they exist in the environment over time frame relevant to risk assessment and regulators. Traditionally, remediation is viewed from the standpoint of parent compound disappearance, and the assumption is that this equates to a cleaner and safer environment. However, stable intermediates produced during remediation, both as individual compounds and as mixtures representing their environmental occurrence. The hypothesis to be tested by the Remediation Product Evaluation Core is that the products of Remediation have different biologic activities compared to the parent compounds or mixtures. The Core will serve to integrate activities of remediation projects with project investigators seeking to understand the biologic activities of Superfund chemicals and their remediation products. Under auspices of the Core, remediation products of PCB and PAH mixtures and of halogenated solvents and metals will be generated and evaluated using an array of assays which measure a variety of biological functions. This will provide the basis of a more accurate assessment of remediation technologies and how to improve them, as well as a more complete understanding of the mechanisms by which Superfund chemicals and their remediation products exert their biological actions.